Year	Measure
1800	667.7
1820	667.7
1913	902.7
1973	1875
1974	1956
1975	2022
1976	2037
1977	2116
1978	2130
1979	2148
1980	2479
1981	2837
1982	3287
1983	3524
1984	3626
1985	3891
1986	3980
1987	4088
1988	3988
1989	3975
1990	3867
1991	4087
1992	4070
1993	4195
1994	4379
1995	4490
1996	4540
1997	4433
1998	4539
1999	4719
2000	4886
2001	5026
2002	5084
2003	5229
2004	5271
2005	5135
2006	4883
2007	4747
2008	4752
2009	4777
2010	4835
2011	4886
2012	4933
2013	4986
2014	5053
2015	5123
2016	5194
2017	5266
2018	5302